1. Field of the Invention
This invention relates to the construction of Vibration Isolation Modules (VIMs) which are typically used on either side of an acoustic aperture of a towed acoustic array to minimize performance degradation due to transmitted mechanical vibrations.
2. Discussion of the Background
Conventional towed arrays have consisted of a towing cable (negatively buoyant to achieve submersion to the required depth), a forward Vibration Isolation Modules (to minimize the transmission of mechanical vibration from the tow cable to the acoustic array), an array of acoustic (and non-acoustic) sensors, and an aft VIM (to minimize transmission of vibration from the "flapping tail" forward to the acoustic array). To perform the required vibration isolation functions, the VIMs, like the suspension of a motor vehicle must not only provide elastic isolation (i.e., the spring function) but must also dissipate the produced vibrational energy (i.e., the damping function).
In the past, VIMs have been constructed that have provided adequate elasticity, albeit for a limited range of tow loads and limited damping. Their effectiveness has been limited, and restricted to a narrow range of operating conditions.